1. Field of the Invention
The present invention relates to a cooling system employing a wet sleeve cylinder liner and more specifically a cylinder liner having an outer surface with a plurality of peaks and valleys to increase the overall outer surface area of the liner and improve cooling efficiency
2. Description of the Related Art
The automotive industry continually demands increased horsepower from vehicle engines. Unfortunately, a direct correlation exists between increased horsepower and heat production by the engine. The presence of heat in an internal combustion engine adversely affects many different components. The continual heat up and cool down of the engine results in the breakdown of components such as gaskets and seals thereby reducing their overall useful life. Additionally, increased heat in a combustion chamber results in the creation of nitrogen oxide. Nitrogen oxide is a pollutant targeted for reduction by the Environmental Protection Agency and Corporate Average Fuel Economy standards developed by the Department of Transportation. Furthermore, an increase in engine temperature requires the upgrade of cooling systems and components such as water pumps and coolers. When these components are upgraded and increased in size, the parasitic drag of the vehicle is also increased and fuel economy is adversely affected.
The greatest concentration of heat produced by an engine is in the combustion chamber. Therefore, to eliminate heat overall from the engine it is best to target heat removal from the combustion chamber area. The chamber includes a plurality of cylinder bores that receive cylinder liners. Each liner is either of a wet-sleeve design or a dry-sleeve design. Liners of a wet-sleeve design are inserted into the cylinder bore and a cooling medium is in direct contact with an outer surface of the liner. The cooling medium may be water, anti-freeze, oil and any combination thereof. In contrast, a dry-sleeve design is not in direct contact with the cooling medium. Instead, a plurality of cooling passages are cast around the cylinder bore to carry the cooling medium. The dry-sleeve design is less effective in reducing heat in the combustion chamber. Having the cooling medium in direct contact with the liner is typically more efficient and allows the engine to be operated at a higher temperature.
Despite the improved efficiency of wet-sleeve cylinder liners as compared to dry-sleeve liners, industry demands for increased horsepower require even more efficient heat removal. Traditionally, the cylinder liner is a cylindrical casing having a generally planar outer surface. Variations include projections on the outer surface. When the outer surfaces of wet-sleeved liners include projections, the liners typically form an interference fit that results in channels formed by the projections contacting a wall of the cylinder bore. These channels transport the cooling medium around the liner. Additionally, the projections are generally not arcuate in order to properly mate the projection to the wall of the bore. The limitation of having a channel to transport the cooling medium is a reduction of the outer surface of the liner in contact with the cooling medium. By limiting the cooling medium to channels that thereby adjust the flow of cooling medium around the liner; the overall efficiency of heat reduction is reduced.
Accordingly, an object of this invention is an improved wet-sleeve cylinder liner whereby heat reduction efficiency in the combustion chamber is increased.
The present invention is directed to a cooling system comprising a cylinder block having a plurality of cylinder bores forming receivers. Each bore has a fixed first predetermined diameter. Positioned into each receiver is a cylinder liner forming a combustion chamber. The liner is cylindrical and has a second predetermined diameter. The second predetermined diameter of the liner is less than the first predetermined diameter of the bore. The first predetermined diameter must be larger than the second predetermined diameter in order to properly receive the liner and a cooling medium such as water, oil or anti-freeze within the receiver.
To further improve the heat reducing efficiency of the liner, the liner of the present invention has an outer surface with a plurality of peaks and valleys. The peaks and valleys increase the overall outer surface area of the liner. The increase in surface area increases the amount of cooling medium in contact with the liner. Therefore, because more cooling medium is in contact with the outer surface of the liner, the heat reduction efficiency improves. The peaks and valleys are positioned along the entire length of the cylinder liner preferably in a generally sinusoidal pattern. More preferably, in addition to being in a generally sinusoidal pattern, the peaks and valleys are also arcuate. The arcuate shape prevents cavitation of the cooling medium and damage to the outer surface. The liner has an inner surface that remains generally planar in order to properly receive a piston.
Further features of the present invention include the casing having a first end and a second end. A flange is at the first end of the cylindrical casing. The flange is integral with the casing and is mated to a counterbore at the top of the cylinder block. The flange, when mated to the counterbore, properly positions the liner within the receiver. The second end of the liner includes a bottom and is received within the bore of the cylinder block.